add docker setup

Dockerfile

@@ -0,0 +1,54 @@
+# Arbiter Dockerfile
+# Multi-stage build for smaller final image
+
+FROM python:3.12-slim as builder
+
+WORKDIR /app
+
+# Install build dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    gcc \
+    libpq-dev \
+    && rm -rf /var/lib/apt/lists/*
+
+# Install Python dependencies
+COPY pyproject.toml ./
+RUN pip install --no-cache-dir build && \
+    pip wheel --no-cache-dir --wheel-dir /wheels -e .
+
+# Final stage
+FROM python:3.12-slim
+
+WORKDIR /app
+
+# Install runtime dependencies
+RUN apt-get update && apt-get install -y --no-install-recommends \
+    libpq5 \
+    && rm -rf /var/lib/apt/lists/* \
+    && useradd --create-home --shell /bin/bash arbiter
+
+# Copy wheels and install
+COPY --from=builder /wheels /wheels
+RUN pip install --no-cache-dir /wheels/* && rm -rf /wheels
+
+# Copy application
+COPY src/ ./src/
+COPY templates/ ./templates/
+COPY alembic.ini ./
+
+# Set ownership
+RUN chown -R arbiter:arbiter /app
+
+USER arbiter
+
+# Environment
+ENV PYTHONPATH=/app/src \
+    PYTHONUNBUFFERED=1 \
+    ARBITER_TEMPLATES_DIR=/app/templates
+
+# Default command (API server)
+CMD ["uvicorn", "arbiter.main:app", "--host", "0.0.0.0", "--port", "8000"]
+
+# Health check
+HEALTHCHECK --interval=30s --timeout=10s --start-period=5s --retries=3 \
+    CMD python -c "import urllib.request; urllib.request.urlopen('http://localhost:8000/health')"